Project evaluates combination of techniques for erosion control in the Center-South

Direct Planting (PD) is one of the most recommended management alternatives to increase productivity, conserving and/or improving the cultivation environment. The technique is efficient in controlling erosion compared to the conventional system, in which vegetation is removed and the soil is disturbed. Now, researchers are seeking to understand whether PD is sufficient to control erosion in different production environments and climatic situations.

The study is developed in support of the Central-South Mesoregional Network project of the Paraná AgroResearch and Applied Training Network (AgroParaná Network), which has financial support from SENAR-PR and the Araucária Foundation. The objective of this subproject is to improve the practice of continuous PD, without interruption for soil preparation, combining conservation management techniques, such as terracing, green manure and level cultivation.

For data collection, three megaplots were installed on a rural property in Guarapuava. In the first, the management already used by the producer was maintained: Direct Planting without terraces, with downhill mechanization – common in many areas in the region –, and without cultivation in the autumn (fallow).

In megaplot two, there was adoption of level mechanization and cultivation of cover crops in the fall. The third megaplot included the construction of terraces and, therefore, level planting. “We are evaluating soil fertility, nutrition and rooting of plants and productivity of crops such as soybeans, corn, wheat and barley. We will examine how the use of other practices combined with Direct Planting, such as terracing, can be effective in controlling erosion”, says the research coordinator, Marcelo Müller.

“We want to show producers that controlling erosion means controlling the variability of soil fertility, which implies different levels of productivity in the same area”, he adds.

During the research, samples of soil and leaf tissue from plants are collected and chemically analyzed in the three megaplots. The root growth of crops also undergoes evaluation, as it is associated with soil conditions and determines the support of the aerial part of the plants and productivity. Furthermore, in megaplot two the biomass production of plants grown for soil cover in the off-season is analyzed, determining the absorption of nutrients and their recycling potential for commercial crops.

According to the researcher, the expectation is that, with the data gathered, it will be possible to understand how changes in management affect production systems, especially in relation to chemical indicators of the soil and plants. In this way, it will be possible to define technical criteria to recommend practices that can improve soil and water conservation, sustainability, productivity and profitability of rural producers.

Water monitoring

The chemical analysis of the material eroded in the megaplots during rain events is also part of the research stages. For this, precipitation must reach a minimum amount for surface water runoff to occur. Together, the chemical quality of the water in the river basin surrounding the megaplots and the crops of other producers is monitored.

The research coordinator explains that the nutrients lost by crops through water runoff and soil sedimentation represent economic losses for producers. “These substances will need to be replaced with fertilizers and correctives, resulting in more costs for the farmer. Furthermore, the accumulation of nutrients available in streams and rivers can cause a process called eutrophication, in which there is an exacerbated growth of algae and a reduction in the amount of oxygen in the water, causing the death of fish and other aquatic species”, points out Müller.